RICERCA ITALIANA     

Dedifferentiated papillary thyroid cancer: clinical, cellular and molecular characteristics; synthesis and pre-clinical development of novel tyrosine kinase inhibitors.

Università di Pisa

Abstract

Dedifferentaiated papillary thyroid carcinoma (DPTC) is chacterized by aggressive growth, metastatic spread and loss of iodide uptake ability, making the tumor resistant to radioiodine; chemotherapy and radiotherapy have a modest, if any, effect, while novel molecules ”tyrosine kinase inhibitors” (TKIs) have promising beneficial antitumoral effects in clinical settings.
Aims of the study are: 1) to characterize, at clinical and molecular level DPTC; 2) to produce novels TKIs molecules; 3) to evaluate TKIs antineoplastic activity in vitro, in preclinical pharmacology studies, in primary cultured DPTC cells.
Patients operated for dedifferentiated papillary thyroid cancer (DPTC) in the Units of Prof. Berti and Prof. Pelizzo (about 50 patients), in the 2 years of the duration of research, will be included in the study. Clinical data of each patient will be accurately registered.
Tissue samples of each patient, will be sent from the Unit of Prof. Berti to the Unit of Prof. Pelizzo for the molecular characterization. Conversely, some tissue samples (about 10) obtained in the Unit of Prof. Pelizzo will be rapidly transported to the Unit of Prof. Berti, to obtain primary cell cultures.
The Unit of Prof. Pelizzo will analyze the genetic expression of several thyrocyte membrane transporters and enzymes involved in maintaining differentiated thyroid functions, such as NIS, PDS, TPO and Tg, and implicated in glucose uptake and its subsequent use, such as the >>>

Principal Investigator

Piero Berti Università degli Studi di PISA

Research Objectives

Papillary differentiated thyroid carcinomas are usually curable by the combination of surgery, radioiodine ablation and thyroid stimulating hormone suppressive therapy, recurrence occurs in 20–40% of patients (Mazzaferri EL, 2002: Schlumberger MJ, 1998). During tumor progression, cellular dedifferentiation occurs in up to 5% of cases and is usually accompanied by more aggressive growth, metastatic spread and loss of iodide uptake ability, making the tumor resistant to the traditional therapeutic modalities and radioiodine (dedifferentiated thyroid cancer; DPTC). Conventional chemotherapy and radiotherapy have a modest, if any, effect on advanced dedifferentiated thyroid cancer (Haugen BR,1999), which is responsible for the vast majority of deaths attributed to thyroid cancer. Therefore, advanced dedifferentiated thyroid cancer represents a therapeutic dilemma and is considered a critical area of research.
MOLECULAR CHANGES IN ADVANCED THYROID CANCER.
In adult sporadic papillary carcinomas, RET/PTC rearrangements are found in 30-40% of cases, RAS mutations in about 10%, and BRAF mutations in around 40% of cases, with no overlap between these mutations (Krause DS, 2005; Braga-Brasaria M, 2003). In papillary carcinomas induced by radiation and in those in childhood, RET/PTC rearrangements have been seen in 50–80% of cases and BRAF mutations in 10% of cases (Krause DS, 2005; Braga-Brasaria M, 2003). Inhibitors of BRAF kinase block the growth of thyroid cancer cells >>>

First Results

EXPECTED RESULTS, UNIT OF PROF. PELIZZO.
PRELIMINARY RESULTS.
Preliminary studies have been conducted by the Unit of Prof. Pelizzo in a limited number (10) of patients with DPTC. Cancers with no 131I uptake had slightly reduced NIS, significantly reduced expression thyroglobulin (Tg) (p< 0·01), thyroperoxidase (TPO) (p=0.01) and pendrin (PDS) (p= 0.03) and significantly increased GLUT-1 (p= 0.01) gene expression levels; and a high frequency of BRAF mutations (77%). BRAFV600E mutation, in metastatic thyroid cancers, is associated with a marked drop in thyroperoxidase (about 30-fold) and pendrin (20-fold) expression and a considerable increase (five-fold) in GLUT-1 expression.
EXPECTED RESULTS.
Differentiated thyroid function gene expression.
NIS, Tg, TPO and PDS mRNAs are expected to be lower in all thyroid cancers than in normal tissues. Recurrences with no 131I uptake will reveal only a slight decrease in NIS transcripts by comparison with primary cancers, but significantly lower Tg, TPO and PDS transcripts. For each thyroid gene, metastases with a positive 131I WBS, probably, will have mRNA levels similar to primary cancers. A correlation will be searched between the expression of Tg, TPO and PDS.
Glucose metabolism gene expression.
By comparison with normal tissues, primary cancers and recurrences will probably show an increase of GLUT-1 mRNA levels, but only the recurrences with no 131I uptake will reveal a >>>

Timescale

24 months

National and international background

INTRODUCTION
Thyroid carcinoma is the most prevalent endocrine malignancy, and accounts for just 1% of all human cancers. Approximately 90% of thyroid malignancies are well-differentiated thyroid carcinomas, which are classified as papillary or follicular based on histopathological criteria. Even though differentiated thyroid carcinomas are usually curable by the combination of surgery, radioiodine ablation and thyroid stimulating hormone suppressive therapy, recurrence occurs in 20–40% of patients (Mazzaferri EL, 2002: Schlumberger MJ, 1998). During tumor progression, cellular dedifferentiation occurs in up to 5% of cases and is usually accompanied by more aggressive growth, metastatic spread and loss of iodide uptake ability, making the tumor resistant to the traditional therapeutic modalities and radioiodine (dedifferentiated thyroid cancer). Conventional chemotherapy and radiotherapy have a modest, if any, effect on advanced dedifferentiated thyroid cancer (Haugen BR,1999), which is responsible for the vast majority of deaths attributed to thyroid cancer. Therefore, advanced dedifferentiated thyroid cancer represents a therapeutic dilemma and is considered a critical area of research.

MOLECULAR CHANGES IN DEDIFFERENTIATED THYROID CANCER
Iodide trapping is a thyrotropin (TSH)-regulated mechanism involving an energy-dependent transport mediated by the Na +/I- symporter (NIS) (Haugen BR,1999; Filetti S,1999) at the basolateral surface of the >>>